Improvement in burglar-alarms



E. HAND.

Burglar-Alarm.

Patented Aug.17,1s7--5.

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EKINS HAND, OF ROCHESTER, NEW YORK, ASSIGNOR OF ONE-HALF HIS RIGHT TOCLARK D. PAGE, OF SAME PLACE.

IMPROVEMENT IN BURGLAR-ALARMS.

Specification forming part of Letters Patent No. 166,696, dated August17, 1875 application filed October 9,1874.

To all whom it may concern:

Be it known that I, EKINS HAND, of the city of Rochester, in the countyof Monroe and State of New York, have invented a certain new and usefulImprovement in Burglar- Alarms; and I do hereby declare that thefollowing is a full, clear, and exact description of the constructionand operation of the same, reference being had to the accompanyingdrawings, in which- Figure 1 is an elevation, showing my improvementapplied to a door. Fig. 2 is an enlarged view of the upper part of Fig.1, showing the pawl drawn down and disengaged from the hammer. Fig. 3 isa perspective view of the crank and rod connection.

This improvement belongs to that class of burglar-alarms in which a bellis connected with the door, and. is sounded upon attempt to open thedoor. Such devices are usually operated by the swinging of the door. Iconnect my alarm with the spindle of the doorknob, so that the alarm issounded upon the attempt to turn the knob, and before the door can bereleased to swing.

The improvements will be fully hereinafter described and pointed out inthe claims.

In the drawings, A indicates the alarm-bell, which is attached by meansof the plate B to the door at any desired distance from the knob C. Thealarm is struck by means of a hammer, D, which is pivoted at c, and hasa tang or stem, 12, projecting on the reverse side of the pivot. On therear side of this tang is a pawl, E, jointed at c to the rod G, whichextends to the knob. The pawl plays loose, like a latch, but is pressedup to the engagement with the tang by means of a spring, H, and on theupper end of the pawl is a hook, d, which catches over the tang, asshown in Fig. 1. Beneath this is a wedge-shaped cam, j, which, when thepawl is drawn down, strikes on a fixed stop, g, and throws the pawlbackward out of engagement with the tang, as shown in Fig. 2. In the actof drawing down, however, the pawl draws upon the tang and elevates thehammer, and the latter, when released by the pawl, strikes upon the bellby means of the reacting spring 70. When the operating-rod G is releasedthe pawl is thrown back to place again by the coiled spring k, whichencircles the rod, and is held by a shoulder or stop, Z, upon thebearing m. In returning to place the hook (I of the pawl slips over andre-engages with the tang of the hammer, and the same is in condition foraction a second time. In this arrangement of the loosely engaging anddisengaging pawl consists the first feature of my invention. It differsfrom other devices in operating the hammer, and being thrown off fromthe engagement by one and the same movement downward, and then re-engaging by the simple reverse movement upward, thereby corresponding withthe action of turning and releasing the knob, as will presently bedescribed.

K is the shank or spindle of the knob, which operates the lock-work. Ithas upon its square part a a crank-arm, L, which fits loosely. As thespindle is turned the crankarm is turned with it. On the outer end ofthe crank-arm is a crank-pin, 19, and on this slips the end of the rodG, which has a hole, 1', for the purpose. When in place on the crank-pinthe end of the rod G is covered by a button, 8, of the crank-arm, whichkeeps it from slipping off. By turning the knob in attempting to openthe door it will be seen that the crank-arm will be correspondinglyturned, and this will operate the rod G downward, and consequently soundthe alarm. But the spindle of the knob cannot be turned sufficiently todraw the lock-catch from its keeper in the jamb, for the reason that apin, 25, on the rod G strikes down upon a fixed bearing, o, and staysthe turning movement of the spindle as soon as the alarm is sounded, andbefore the lock-catch moves from the keeper. The device, therefore,serves as a look as well as an alarm. When it is desired not to use thealarm, but to employ the knob in the ordinary way, the button 8 isturned down, the end of the rod disengaged from the crankpin, and therod then placed over a pin or stay, 10, which clears it of the crank,and holds it out of the way. In this arrangement of the crank-armfitting over a square bearing of the knob-spindle, and combined with arod extending to the bell, consists the second feature of my invention.By this means the alarm is sounded on the initial movement of the knob,and before the door can be opened, and the device also constitutes alock in itself.

The crank and rod might be connected with the bell in various ways, soas to sound the alarm on -the turning of the knob; but the connection ofthe same with the pawl E is simple and effective. By the use of thispawl, pivoted only to the upper end of the rod G, the reciprocatingaction of the rod is best accommodated, and the action is alternate-theeffect being produced without any complication of mechanical parts, suchas are generally employed in burglar-alarms.

Having thus described my invention, what I claim as new isl. Thecombination, with the hammer D and rod G, connected with the spindle ofthe door-knob, of the sliding pawl E pivoted to the end of the rod, andprovided with the hook d and cam f for alternately engaging with anddisengaging from the tang of the hammer, as herein shown and described.

2. The combination, with the knob-spindle K, of the crank-arm L and rodG, the latter connecting with the hammer-lever, and having a pin, 15,and stop 41, the whole constructed to operate, substantially asdescribed, whereby the knob sounds the alarm in the initial movement,but is stopped before withdrawing the latch-bolt from its keeper, as setforth.

In witness whereof I have hereunto signed my name in the presence of twosubscribing witnesses.

EKINS HAND. Witnesses:

RF. Oseoon, EDWIN B. SCOTT.

